Self-healing inner tube



Sept, 4, 192s.

' w. FETTER SELF HALING INNER TUBE Filed Oct'. 13. 1924 amm m n Mylviatentecl Sept. 4,' 1928.

UNITED STATES A 1,683,454 PATENT orricr..

WILLIAM FETTER, 0F BALTIMORE, IMARYLAND.

snm-HEALING INNER TUBE.

Application flied october 13, 1924. serial No. 743,244.

and confining it to the desired area intended to form the pocket, thespread of this material tending to prevent proper adhesion ofv therubber where it is joined to form the pocket, and it has further beenfound that the presence of the self-healing compound duringvulcanization interferes with the curing of the rubber.

The present invention relatesv to the production of a tube with a pocketfor self-healing compound which may be vulcanized prior to theintroduction of the compound, the pocket being so formed and arranged asto confine the compound when introduced to the desired area of the tubewall to be thus treated.

The invention also relates to the method of making a self-healing tubehaving the char acteristics above out-lined.

In the practice of my method I first produce the desired length oftubing of unvulcanized rubber having a portion of the area usually7comprising the tread and as much of the side walls as it is considereddesirable to treat in this way, bounded by or lying between v twolongitudinal shoulders, which when the tubel is laid flat with thisportion upwards, may be described as forming a shallow groove orchannel. The tubing thus formed of unvulcanized or raw rubber is thenvulcanized, and after vulcanization either before or after splicing atthe ends, the tube is laid flat with the groove referred to upward, andthe groove is filled with self-healing compound and covered by means ofa cover stri-p preferably of rubber which extends about thecircumference' of the tube on the outside and which should beA reducedin thickness at the e ges so as to produce a smooth exterior surface ofthe tube.

These edges overlap the groove to a consider` able extent lon both sidesand are secured to the side walls of the tube in any suitable manner, asby means of a. vulcanizing cement which is curedlby heat treatment.. l

This cover strip may be formed of'rubber,

thickest at the centre and tapered at both i edges, and may toadvantagebe made with the outer surface flat or otherwise shorter thanthe inside surface, and covered by means of a comparativelyinelasticfabric which is placed in the mold with the strip when thelatter is vulcanized, and which when the strip is applied outside of thetube, on account of the longer arc of the fabric as compared to the arcof the inside of the strip, tends to compress laterally the rubber'forming the strip and the outside of the pocket, giving an additionalprotection against punctures on account of this lateral compression.

In the accompanying drawing I have illustrated a tube constructed inaccordance with my inventiom-` Figure l being a transverse cross-sectionofthe completed tube.

Figure 2 a side elevation, partly in section. Figure 3 a transversesection through the cover strip, before it is applied'to the tube,

showing a portion thereof in perspective.

Referring tothe drawings by numerals, each of which is used to indicatethe same or similar parts in the different figures, the self-healingtube consists of a tubular member l formed of vulcanized rubber andhaving 'in its outer circumferential surface a groove 2 which may be ofany desired width and which is formed between r'shoulders 3 y whichextend longitudinally or circumferen-` tially about the tube in thedirection of its long circumference, puncture healing mate-' rial 4 inthe groove and cover strip 5.

The groove 2 is filled or partially filled with puncture-healing plastic4; of any suitable composition and closed by means of a cover strip 5 ofrubber covering the groove and having side edge portions 6 extendingbeyond the groove on each side and secured to the side walls `of thetube in any suitable manner, preferably by cementing bymeans of aheat-treated or vulcanizing cement.'

This cover strip 5 may be formed with its outer surface 7 fiat orotherwise of less area than the inner surface 8 which is convex,

and this outer surface 7 is covered 'with comparatively inelastic fabric9 which is secured to the surface preferably byvulcanization, the fabricbeing placed, in the mold when the striplis' formed. The formation i andplacing of the cover .strip in this Waycauses the convex surface 8 to bebent inwardly on the are of the tread surface of the tire when the tire'and tube are inflated,

rubber forming the cover strip and increasing the puncture-closingeffect of the entire structure by providing an excess of elasticrubberto till the openings thus formed.

. I have thus described specifically and in detail a single embodimentof my invention together with the method of manufacture which is also=afeature of my invention, the description *being specific and in fulldetail in order that the nature and operation of the invention may befully understood; however, the specific terms herein are useddescriptively rather than in a limiting sense, the scope of theinvention being defined in the claims.

What I claim and desire to secure by Letters Patent is:

1. In an inner tube for pneumatic tires, a tubular member of vulcanizedrubber having a. channel extending longitudinally of the tread portion,puncture-healingr plastic in the channehand'a cover strip covering thechannel and secured to the tube at each side of the channel.

2. An inner tube vfor pneumatic tires having longitudinally extendingrshoulders spaced apart to form a channel including the tread portlon ofthe tube, puncture-healing:

material in the channel and a cover strip 30 holding thepnncture-healing;r material in the channel and secured to the tubularmember at each side of the channel.

3. An inner` tube for pneumatic tires havy strip holding thepuncture-healing material.

in the channel and secured to the tubular member at each side of thechannel, the cover strip beingcomposed of rubber and having a fabriclcoveringY on the outside whereby the rubber is placed under compressionlaterally when thetube is inflated in the casing.

4. An inner tube for pneumatic tires having,r longitudinally extending'shoulders spaced apart to form a channel, puncturehealing material inthe channel and a cover strip holding the puncture-healing material inthe channel and secured to the tubular member at each side of thechannel, the cover strip being composed of resilient material and havingan outer covering of fabric, the inside Aof the cover strip being convexWhen the strip is flat, so that the bending of the` cover strip when thetube is inflated placesthe resilient material under lateral compression.

Si gned by me at Baltimore, Maryland, this 8th day of October, 1924.IVILLIAM FETTER.

shoulders

